Empathy for others is a trait that must be learned -- and parents are the best people to teach it. Volunteering together is an excellent way to increase your child's social and emotional growth while spending quality time together.

It's no secret that obesity has become a major health problem in the U.S. -- for both adults and kids. Roughly one in five children between the ages of 6 and 11 is obese, according to the Centers for Disease Control, and many more are overweight. So what's to blame? Lack of exercise and poor food choices are prime suspects. But so is portion control -- which for many families has spiraled out of control.

In the last 20 years, people's idea of a serving size has ballooned, according to the National Institutes of Health. Two decades ago, the average bagel was 3 inches wide and 140 calories; today, it's 6 inches wide and 350 calories. Back then, cheeseburgers had 330 calories; now they've nearly doubled. And the average serving of soda has more than tripled -- from 6.5 ounces and 85 calories to 20 ounces and 250 calories.

"The media keeps telling us we need to eat more; everything is just bigger when you see it," says Dr. Virginia Keane, associate professor of pediatrics at the University of Maryland Medical School. "And we have all-you-can-eat restaurants. We've lost control and community knowledge of what's a normal portion."

A portion is a fistful -- the eater's fistful, according to Keane. (If you or your child is very active, you may need more. If you're inactive, you may need less.) Just by reducing your food intake to that amount, you'll help your family lose weight or at least maintain it. And it's easier than you think. Here are some suggestions for keeping portions in check:

Cook and eat at home.

The simplest way to avoid supersized portions is to prepare and serve your own meals. The key, according to Keane, is to cook only the amount you'll need for that meal (no leftovers!) and serve everything on individual plates, not family style. The only exceptions: vegetables and salad. There's no limit on veggies (as long as they're not drenched in butter or doused with full-fat dressing), so everyone can take what they want.

Go halvsies.

If you're at a restaurant, split dishes between two adults. If the kids' meals are twice the appropriate portion size, do the same with them. If your family tends to eat whatever's in front of them, ask to have half the portion put in a to-go container before it even hits the table.

Snack smaller.

When you sit down in front of the TV or computer, don't bring that bag of pretzels or cookies with you. Instead, scoop out a small amount and put it in an individual bowl -- and don't let yourself go back for more. Put the rest of the bag on a top shelf or at least out of sight. Better yet, cut up some fruit and put it in individual bowls. Or pass out fruit roll-ups or cheese sticks -- one per person.

Downsize, don't supersize.

Instead of getting the double-patty cheeseburger with bacon, order the plain junior cheeseburger instead. If your value meal comes with medium fries and drink, opt to go a la carte and order smalls. Ask for a kid-size portion of ice cream instead of one, two or three regular scoops. If it doesn't feel like enough, remind yourself that that's what size a serving of ice cream used to be anyhow.

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Gail Belskyhas worked on a variety of women's publications, including Parents, Working Mother and All You, and she recently wrote a book for women, entitled The List: 100 Ways to Shake Up Your Life. She is the managing editor of Your Family Today.